How does Gas Exchange happen?

This happens in the Lungs where oxygen is transported to the bloodstream. How this happens comes down to the alveoli where it happens. The Alveoli are adapted to this by having: Massive surface area : Volume ratio, Tiny walls, A moist lining for dissolving gases and a good blood supply. The Capillary next to the Alveoli gives it Carbon Dioxide and in return gets Oxygen. The Blood in the stream is Deoxygented [no oxygen but lots of CO2] so diffusion can happen quickly. The oxygen is diffused in and is now carried to its destination